from http://www.devshed.com/c/a/MySQL/Error-Handling-Examples/
Error Handler Examples
Here are some examples of handler declarations:
If any error condition arises (other than a NOT FOUND ), continue execution after setting l_error=1 :
DECLARE CONTINUE HANDLER FOR SQLEXCEPTION
SET l_error=1;
If any error condition arises (other than a NOT FOUND ), exit the current block or stored program after issuing a ROLLBACK statement and issuing an error message:
DECLARE EXIT HANDLER FOR SQLEXCEPTION
BEGIN
ROLLBACK;
SELECT 'Error occurred – terminating';
END;
If MySQL error 1062 (duplicate key value) is encountered, continue execution after executing the SELECT statement (which generates a message for the calling program):
DECLARE CONTINUE HANDER FOR 106 2
SELECT 'Duplicate key in index';
If SQLSTATE 23000 (duplicate key value) is encountered, continue execution after executing the SELECT statement (which generates a message for the calling program):
DECLARE CONTINUE HANDER FOR SQLSTATE '23000'
SELECT 'Duplicate key in index';
When a cursor fetch or SQL retrieves no values, continue execution after setting l_done=1 :
DECLARE CONTINUE HANDLER FOR NOT
FOUND
SET l_done=1;
Same as the previous example, except specified using a SQLSTATE variable rather than a named condition:
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000 '
SET l_done=1;
Same as the previous two examples, except specified using a MySQL error code variable rather than a named condition or SQLSTATE variable:
DECLARE CONTINUE HANDLER FOR 1329
SET l_done=1;

错误处理例子
有几种错误处理的声明形式：
§ 如果任何错误（不是 NOT FOUND ） , 设置 l_error 为 1 后继续执行：
DECLARE CONTINUE HANDLER FOR SQLEXCEPTION
SET l_error=1;
§ 如果发生任何错误（不是 NOT FOUND）， 执行 ROLLBACK和产生一条错误消息后退出当前块或存储过程。
DECLARE EXIT HANDLER FOR SQLEXCEPTION
BEGIN
ROLLBACK;
SELECT 'Error occurred – terminating';
END;
§ 如果 MySQL 1062错误 (重复的健值 )发生，执行 SELECT语句（向调用程序发一条消息）后继续执行
DECLARE CONTINUE HANDER FOR 106 2
SELECT 'Duplicate key in index';
§ 如果 SQLSTATE 2300错误 (重复的健值 )发生，执行 SELECT语句（向调用程序发一条消息）后继续执行
DECLARE CONTINUE HANDER FOR SQLSTATE '23000'
SELECT 'Duplicate key in index';
§ 当游标或者 SQL 选择语句没有返回值时，设置 l_done=1 后继续执行
DECLARE CONTINUE HANDLER FOR NOT
FOUND
SET l_done=1;
§ 此例除了用 SQLSTATE 变量而不是命名条件以外，跟前一个例子一样
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000 '
SET l_done=1;
§ 此例除了用 MySQL 的错误码变量而不是命名条件或者 SQLSTATE 变量以外，跟前两个例子一样
DECLARE CONTINUE HANDLER FOR 1329
SET l_done=1;